| 摘要 |
PROBLEM TO BE SOLVED: To extend a dynamic range even when using a low voltage power supply. SOLUTION: A reference voltage setting part 2 feeds back a part of an input signal voltage Vin of an operational amplifier 11 to a reference voltage Vref of the operational amplifier 11. By this process, an output voltage from the reference voltage setting part 2 is additionally applied to the original reference voltage Vref of the operational amplifier 11. Thus, amplification in an input range area where linearity of an amplification factor is poor is avoided and amplification in an input range area where the linearity of the amplification factor is always good is performed. Moreover, in order to calculate a final output voltage in an original area where the linearity is poor, an output calculating part 3 inputs an output voltage from the reference voltage setting part 2, detects a moving amount of the input range. By this process, a final output voltage is correctively calculated.
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